TRIM26‐Mediated CBX6 Ubiquitination Triggers NETosis to Drive Bladder Cancer Tumor Growth via the CNPY2/NF‐κB Signaling Pathway

Neutrophil extracellular traps (NETs) play a critical role in bladder cancer (BCa) progression, but the intrinsic molecular drivers within tumor cells that orchestrate NET formation remain largely unknown. This study aimed to investigate whether and how the E3 ubiquitin ligase TRIM26 influences BCa malignancy by regulating NET formation. Analysis of public cohort data revealed a significant positive correlation between TRIM26 expression and neutrophil infiltration in BCa, which was confirmed in our clinical samples showing markedly enhanced neutrophil infiltration and NET formation in tumor tissues compared with adjacent normal tissues. Functional assays demonstrated that NETs promoted BCa cell proliferation, migration, invasion, and epithelial-mesenchymal transition in a TRIM26‑dependent manner. Mechanistically, TRIM26 directly bound to Chromobox 6 (CBX6) and mediated its ubiquitination and degradation. CBX6 transcriptionally represses canopy FGF signaling regulator 2 (CNPY2) by catalyzing H2AK119ub1 deposition on its promoter. Degradation of CBX6 led to CNPY2 upregulation, which activated the NF‑κB pathway and stimulated IL‑8 secretion. Secreted IL‑8 recruited neutrophils and induced NET formation, establishing a positive feedback loop that fuels tumor progression. In vivo experiments confirmed that disrupting NETs with DNase I significantly inhibited TRIM26 overexpression‑driven tumor growth and metastasis. Collectively, this study uncovers a TRIM26/CBX6/CNPY2 signaling axis that drives NET formation via the NF-κB/IL-8 pathway to promote BCa progression, providing novel mechanistic insights and potential therapeutic targets for combating NET-driven BCa malignancy.